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二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...寸。官方叫版本Version。Version 1是21 x 21的矩阵，Version 2是 25 x 25的矩阵，Version 3是29的尺寸，每增加一个version，就会增加4的尺寸，公式是：(V-1)*4 + 21（V是版本号） 最高Version 40，(40-1)*4+21 = 177，所以最高是177 x 177 的正方形。
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data.table vs dplyr: can one do something well the other can't or does poorly?
...;% group_by(z) %>% do(data.frame(.$x[1:2], .$y[1]))
DT[, quantile(x, 0.25), by = z]
DF %>% group_by(z) %>% summarise(quantile(x, 0.25))
DT[, quantile(x, c(0.25, 0.75)), by = z]
DF %>% group_by(z) %>% do(data.frame(quantile(.$x, c(0.25, 0.75))))
DT[, as.list(summary(x)), by = z]
DF %...
Using global variables in a function
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253
I disagree that the reason Python requires the global keyword is because globals are dangerous. Rather, it's because the language doesn't ...
List columns with indexes in PostgreSQL
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25
For anyone trying to find indexes in a populated database: this query works great, but change the and t.relname like 'test%' line to the ta...
PowerShell script to return versions of .NET Framework on a machine?
...ion]'4.5.2'
393295 = [version]'4.6'
393297 = [version]'4.6'
394254 = [version]'4.6.1'
394271 = [version]'4.6.1'
394802 = [version]'4.6.2'
394806 = [version]'4.6.2'
460798 = [version]'4.7'
460805 = [version]'4.7'
461308 = [version]'4.7.1'
461310 = [version]'4.7...
Should I use Java's String.format() if performance is important?
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25
This looks a lot like the sort of microbenchmark that is going to be optimized away in a very unuseful manner.
– Davi...
Clearing using jQuery
...net/rPaZQ/23.
– Timo Kähkönen
Mar 25 '13 at 1:49
28
Problem is, this at least temporarily makes...
Pass Method as Parameter using C#
...enEgil Hansen
12.9k77 gold badges3333 silver badges5252 bronze badges
54
...
Determine a user's timezone
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answered Mar 25 '14 at 3:47
Matt Johnson-PintMatt Johnson-Pint
182k6161 gold badges356356 silver badges484484 bronze badges
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How to change the style of alert box?
...ize:1.2em;
color:#069;
}
#credits {
position:relative;
margin:25px auto 0px auto;
width:350px;
font:0.7em verdana;
border-top:1px solid #000;
border-bottom:1px solid #000;
height:90px;
padding-top:4px;
}
#credits img {
float:left;
margin:5px 10px 5px 0p...